
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">


<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    
    <title>TableGen Deficiencies &mdash; LLVM 3.7 documentation</title>
    
    <link rel="stylesheet" href="../_static/llvm-theme.css" type="text/css" />
    <link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
    
    <script type="text/javascript">
      var DOCUMENTATION_OPTIONS = {
        URL_ROOT:    '../',
        VERSION:     '3.7',
        COLLAPSE_INDEX: false,
        FILE_SUFFIX: '.html',
        HAS_SOURCE:  true
      };
    </script>
    <script type="text/javascript" src="../_static/jquery.js"></script>
    <script type="text/javascript" src="../_static/underscore.js"></script>
    <script type="text/javascript" src="../_static/doctools.js"></script>
    <link rel="top" title="LLVM 3.7 documentation" href="../index.html" />
    <link rel="up" title="TableGen" href="index.html" />
    <link rel="next" title="Debugging JIT-ed Code With GDB" href="../DebuggingJITedCode.html" />
    <link rel="prev" title="TableGen Language Introduction" href="LangIntro.html" />
<style type="text/css">
  table.right { float: right; margin-left: 20px; }
  table.right td { border: 1px solid #ccc; }
</style>

  </head>
  <body role="document">
<div class="logo">
  <a href="../index.html">
    <img src="../_static/logo.png"
         alt="LLVM Logo" width="250" height="88"/></a>
</div>

    <div class="related" role="navigation" aria-label="related navigation">
      <h3>Navigation</h3>
      <ul>
        <li class="right" style="margin-right: 10px">
          <a href="../genindex.html" title="General Index"
             accesskey="I">index</a></li>
        <li class="right" >
          <a href="../DebuggingJITedCode.html" title="Debugging JIT-ed Code With GDB"
             accesskey="N">next</a> |</li>
        <li class="right" >
          <a href="LangIntro.html" title="TableGen Language Introduction"
             accesskey="P">previous</a> |</li>
  <li><a href="http://llvm.org/">LLVM Home</a>&nbsp;|&nbsp;</li>
  <li><a href="../index.html">Documentation</a>&raquo;</li>

          <li class="nav-item nav-item-1"><a href="index.html" accesskey="U">TableGen</a> &raquo;</li> 
      </ul>
    </div>


    <div class="document">
      <div class="documentwrapper">
          <div class="body" role="main">
            
  <div class="section" id="tablegen-deficiencies">
<h1>TableGen Deficiencies<a class="headerlink" href="#tablegen-deficiencies" title="Permalink to this headline">¶</a></h1>
<div class="contents local topic" id="contents">
<ul class="simple">
<li><a class="reference internal" href="#introduction" id="id1">Introduction</a></li>
<li><a class="reference internal" href="#known-problems" id="id2">Known Problems</a></li>
</ul>
</div>
<div class="section" id="introduction">
<h2><a class="toc-backref" href="#id1">Introduction</a><a class="headerlink" href="#introduction" title="Permalink to this headline">¶</a></h2>
<p>Despite being very generic, TableGen has some deficiencies that have been
pointed out numerous times. The common theme is that, while TableGen allows
you to build Domain-Specific-Languages, the final languages that you create
lack the power of other DSLs, which in turn increase considerably the size
and complexity of TableGen files.</p>
<p>At the same time, TableGen allows you to create virtually any meaning of
the basic concepts via custom-made back-ends, which can pervert the original
design and make it very hard for newcomers to understand it.</p>
<p>There are some in favour of extending the semantics even more, but making sure
back-ends adhere to strict rules. Others suggesting we should move to more
powerful DSLs designed with specific purposes, or even re-using existing
DSLs.</p>
</div>
<div class="section" id="known-problems">
<h2><a class="toc-backref" href="#id2">Known Problems</a><a class="headerlink" href="#known-problems" title="Permalink to this headline">¶</a></h2>
<p>TODO: Add here frequently asked questions about why TableGen doesn&#8217;t do
what you want, how it might, and how we could extend/restrict it to
be more use friendly.</p>
</div>
</div>


          </div>
      </div>
      <div class="clearer"></div>
    </div>
    <div class="related" role="navigation" aria-label="related navigation">
      <h3>Navigation</h3>
      <ul>
        <li class="right" style="margin-right: 10px">
          <a href="../genindex.html" title="General Index"
             >index</a></li>
        <li class="right" >
          <a href="../DebuggingJITedCode.html" title="Debugging JIT-ed Code With GDB"
             >next</a> |</li>
        <li class="right" >
          <a href="LangIntro.html" title="TableGen Language Introduction"
             >previous</a> |</li>
  <li><a href="http://llvm.org/">LLVM Home</a>&nbsp;|&nbsp;</li>
  <li><a href="../index.html">Documentation</a>&raquo;</li>

          <li class="nav-item nav-item-1"><a href="index.html" >TableGen</a> &raquo;</li> 
      </ul>
    </div>
    <div class="footer" role="contentinfo">
        &copy; Copyright 2003-2015, LLVM Project.
      Last updated on 2015-09-08.
      Created using <a href="http://sphinx-doc.org/">Sphinx</a> 1.3.1.
    </div>
  </body>
</html>